Such a belt spool is known from the DE 200 06 619 U. On the locking disc, a locking catch is arranged which can be guided into teeth, fixed to the housing, of a frame of the belt retractor. In this state, the locking disc is blocked against a rotation relative to the frame of the belt retractor. As the spool body rests against the locking disc via the torsion rod, in this state no belt band can be withdrawn from the belt spool, as long as the torque acting on the spool body is not greater than the torsion resistance moment of the torsion rod. When the torsion resistance moment of the torsion rod is exceeded, a relative rotation occurs between the spool body and the locking disc, which leads to a withdrawal of belt band from the belt spool, which in turn leads to an increased forward displacement of a vehicle occupant who is restrained by the safety belt. This greater forward displacement serves in a known manner to reduce force peaks in the safety belt.
When the torsion resistance moment of the torsion rod is exceeded and the torsion rod is twisted, an increase in length of the torsion rod occurs. In order to prevent the locking disc from becoming detached from the spool body owing to the increase in length, in the known belt spool a shoulder is provided, constructed in one piece with the belt spool, which is flanged over an outer edge of the locking disc. In this way, an axial fastening of the locking disc on the spool body is produced, whilst the locking disc can continue to rotate relative to the spool body.
The object of the invention consists in further developing the belt spool of the type initially mentioned to the effect that the fastening of the locking disc on the spool body is improved.